1892.] - The Difficulties in the Heredity Theory. 553 
wear (i. e., use), and conversely in the degeneration of the 
crown, disuse foreshadows atrophy and disappearance. 
Upon the whole, with some exceptions which we do not at 
present understand, the course of evolution of the teeth 
supports the evidence derived from the skeleton, that, whether 
any true causal relation has existed or not, the lines of indi- 
vidual transformation in the whole fossil series preceded those 
of race transformation. 
pe ae 
seus inte: or THE Human Upper Morars.—Fig. uf enim 11r É a lower eocene mon- 
key. Fig. 10,—4 An upper eocene monkey ey. Fig. 12 = 12.--= Esquimaux ; 12, negro. 
See addition of “ talon,” Ay, to ‘* trigon ” composed of 
The Rise of New Organs—We owe to Dr. Arbuthnot Lane a 
most interesting series of studies upon the influences of various 
occupations upon the human body. He proves conclusively 
that individual adaptation not only produces profound modifi- 
cations in the proportions of the various parts, but gives rise 
to entirely new structures. 
His anatomy and physiology of a shoemaker’ shows that 
the lifelong habits of this laborious trade produce a distinct 
type, which if examined by any zoological standard would be 
unhesitatingly pronounced a new species—homo sartorius. 
The psychological analysis which a Dickens or Balzac would 
draw, showing the influences of the struggle for existence 
upon the spirit of this little tailor could not be more pathetic 
than Dr. Lane’s analysis of his body. The bent form, the 
crossed legs, thumb and forefinger action, and peculiar jerk of 
the head while drawing the thread, are the main features of 
sartorial habit. The following are only a few of the results: 
The muscles tended to recede into tendons and the bony sur- 
faces into which they were inserted tended to grow in the 
1Journal of Anatomy and Physiology, 1888, p. 595. 
39 
